Blackboard eraser



Jan. 2, A. A ELNETT BLACKBOARD ERASER Filed D90. 10, 1932 INVENTOR. ANTHONY A. N577 W W ATTORNEY.

Patented Jan. 2, 1934 UNITED STATES PATENT OFFICE 1,942,205 BLACKBOARD ERASER Anthony A. Elnett, New York, N. Y.

Application December 10, 1932 Serial No. 646,671

8 Claims.

This invention relates to black board erasers in general and more especially to erasers for use on black boards composed of slate or the like.

Slate which is so extensively used for black boards in the United States today is excessively porous. As a result, the chalk particles of the crayon used when forming a mark on the board readily enter the pores of the board and while the exterior chalk particles may be removed so as to destroy the legibility of the mark so formed a large quantity of the chalk particles are impressed into some of the pores of the board with each mark. As a result of the foregoing, frequently after a days use, a black board would have changed from its natural color black to a light gray when its effectiveness as a background for white chalk would be materially impaired.

It has been the custom due to the aforesaid condition periodically to wash the boards with water. It has however been found that a water wash alone would not entirely remove all of the chalk particles. In fact, a careful analysis of the boards in use for several years seems to indicate that the water actually served to pack the chalk particles more compactly into the pores. Possibly the outermost layers of chalk particles were removed by the water but some of the water would enter the pores to mix with the chalk particles there present and merely facilitate burying the same more deeply into the pores and in a more compact condition.

The felt of which the black board erasers so extensively used today are composed did not help the situation. Felt was preferred because it absorbed chalk particles when rubbed across a board. The felt of the black board erasers therefore did not'merely remove the chalk particles from the board but actually to a large extent at least transferred the chalk particles from the board to the erasers. As a result, the longer the eraser was used at one time, the more saturated it became with chalk particles. Consequently it would actually function to spread the chalk particles over a large area of the black board in a cloudlike' film.

From the foregoing, it must be apparent that what was happening was not the effective removal of the chalk particles from the black board but rather a removal of the legibility of a certain mark formed on the board with a resulting gradual destruction of the effective original color of the black board.

Attempts have recently been made to counteract the chalk absorbing properties of the slate black boards and in addition to take advantage of the chalk absorbing properties of the felt black board eraser, as for instance by combining an abrasive with the felt. To this latter end, it is one of the main objects of the present invention to provide an improved black board eraser at least partly composed of felt to be used ona slate black board, which eraser will effectively remove the chalk particles on the board, not only from the surface but also from the pores of the slate.

Among the objects of the present invention, it is also aimed to provide an improved black board eraser for use with a slate black board consisting of alternate rows of felt and fine wire bristles in which the felt will serve to support the fine wire bristles in their predetermined positions and in their predetermined erect condition so that the extremities of the wires forming the bristles will be maintained in position effectively to engage the black board during use.

It is still another object of the present invention to provide an improved black board eraser composed of alternate rows of felt and fine wire bristles in which the innermost rows of felt are secured to the base of the eraser by the same means which secure the wire bristles in place and by one and the same operation.

These and other features, capabilities and advantages of the invention will appear from the subjoined detail description of specific embodiments thereof illustrated in the accompanying drawing in which Figure 1 is a perspective of one embodiment;

Fig. 2 is an enlarged section on the line 22 of Fig. 1;

Fig. 3 is a fragmental perspective showing a portion of the felt before attached in place;

Fig. 4 is a perspective of a group or set of wire bristles before positioned in place;

Fig. 5 is an enlarged fragmental end View partly in section of another embodiment of the invention; and

Fig. 6 is a fragmental longitudinal section on the line 6-6 of Fig. 5.

In the embodiment illustrated in Figs. 1 to 4 inclusive, there is provided a base 1 composed of wood or the like which is preferably provided with a plurality of rows of recesses 2 the rows extending longitudinally of the base 1, that is 1 parallel with the elongated lateral faces 3, 3.

In the process of manufacture, it is intended that there shall be secured to this base 1, alternate rows of felt and wire bristles. In the present instance, there are provided six rows or layers of felt and five rows of wire bristles. The position of the wire bristles is determined by the recesses 2.

The six layers of felt consist of two outer single layers 4 and 5, and two sets of double layers 6 and 7. The double layer 6 consists of the individual layers 6 and 6, see Fig. 3. The double layer 7 consists of the individual layers '7 and '7 similar to the double layer 6.

Each of these double layers is formed by a piece of felt having two individual layers and provided with a cut 8 extending about twothirds the thickness of the felt so as to facilitate bending the double layer along this incision 8 so that the faces 9 and 10 of the doublelayer 6 will face one another when in position upon the base 1.

The outer layer 4, see particularly Fig. 2, has a row of staples 11 passed through its outer lower edge bent over. When the staples 11 are so pierced into the lower outer edge of. the layer 4, there will of course be a tendency on the part of the layer 4 to press inwardly.

Similarly,.the layer 5 has i'tslower outer edge secured by arow of staples 12, see Fig. 2, to the base 1. The layers land 5 are preferably secured in place on the base-1 adjacent to a row of recesses 2. Preferably one of the outer layers 4 or v5 is first secured in place. Assume thatthe layer 4 is so secured in place, thereupon a row of wire bristles is secured in place. The wire bristles are groupedsee the group 13 illustrated in Fig. 4. staple 14 is positioned about half way between the ends of said group 13 and then driven home into the base 1, see Fig. 2. After positioning the group 13 in alinem'ent with one of the recesses 2 by sod'riving the staple 14 home, the medial portion of the group of wire bristles I3 will be forced into a recess 2 and thereby cause :the free ends of the wire bristles to move toward one another into erect position adjacent to the layer 4 as indicated in Fig. 2.

Afterthis row of bristles designated for convenience row A isso secured in place, the double ifelt layer 6 is next secured in place and this is done preferably simultaneously when securing the secondrrow of wire bristles, to wit the row B in place. The group of bristles of the row B are similarly alined with the recesses '2 of the second row. This second row of bristles 33 .however is first positioned between the layers 6 and 6 of felt and then secured in place by the staples 15, which staples 15 first grip the bristles, then pass through the felt and finally into the wood in 'alinement with the recesses When the bristles B are so fixed in place, they will similar-1y cooperate with the recesses 2 to be bent into erect position.

Thereupon, the bristles of the row 0 are secured in place, being first alined with the third row of recesses-2 and then secured in place by the staples 16. The bristles of the row -C, however,

are secured direct to the base 1 as distinguished from the row :33. Thereu-pon, the double layer of felt '7 is positioned in place and secured in ,place by the bristles rorirring the row .D which are first positioned between the layers 7 and 7 and thereupon al-ine'd with the fourth row of recesses 2 and thereupon secured in place by staples.

The bristles of the row D and the double layer of felt 7 are secured in place similar to the mannor in which the bristles of the row B :and the double layer of felt 6 are secured in place. Thereupon, the bristles of the -row'E are secured place in the fourth row or recesses-.2, and finally the layer of felt 5 is secured in place as aforesaid by means of the staples 12.

In the'embodiment illustrated in Figs. 5 and 6 in place of the base 1 composed of a single piece of wood, there is provided a veneer base composed of several plies of wood formed in the usual way with the grain running in opposite directions.

In the present instance, the base here is composed of three plies 1'7, 18 and 19. Here the rows of recesses, to wit the recesses 2 are merely formed in the upper ply 17, since the staples here, see for instance the staples 20 in Fig. 6, preferably pass through the outer layer 19 and are clinched over as indicated.

The wire bristlesvare preferably composed of fine wire of about seven-thousandths of an inch in thickness. With bristles of this thickness, it has been found that by means of the alternate layers of felt, the bristles are maintained in their erect condition and in their proper position relative to one another, the layers of felt serving as braces or reinforcements. Without such felt, the bristles quickly become distorted when used and before longamany of .the'bri'stles will be so positionedthat-their extreme free ends-will not be positioned to do any brushing or polishing.

With the presentinventicn, it is an object of course to take advantageof the abrasive effect afforded by the free ends'of the bristles so that these free ends may penetrate theminute pores-l05 of theslate and thereby eirectively'disledge the chalk particles.

When the'bristl-es are once bent over so that their free ends are not in position to engage the slate, this chalk dislodging action cannot be effectively pertormed.

The felt is of course moreyieldable than the wire bristles and consequently the felt layer-scan be longer than the bristles as illustrated Fig. 6.

In the erasing action the felt will up the 115 particles as it is brushed across the board in the well known manner. The bristles will serve to "dislodge the chalk particles from the line .pores'of the board. 7

Furthermore, :as aforesaid, it is desirous of 31 20 maintaining the wire bristlesso that their free ends will be inposition to engage the slate or rather the chalk particles in the pores of the slate and the snug engagement "of the wire bristies between adjacent layers of felt will con- 125 tribute-materially tomaintai-n'i-ng the wire bristles in their most effective .abrasing "condition. other Words, the felt layers when so snugly engaging the wire bristles will serve to brace :or position the wire bristles and protectthem against 1350 collapsing or bendmg over into an ineffective abrasing position.

It is obvious that various :changesand modifications :may be made to thedeta'ils of :oonstruction without departing from the general spirit il '85 of the invention as set forth in the appended claims.

I claim:

1. The combination with-abase, ofza :double iayq er of felt composed of two individual layers :de- '140 fined from one another by an incision, the individual layers being folded over onto one another with the incision disposed at the outerrside of the fold, a row of Wire bristles disposed :between :said individual layers of felt, .and'means for securing the inner ends of said bristles and said double layer of felt at its incision to said base.

2. The combination with a base, of a double layer of felt composed of two individual layers defined from oneanother-by'an incision, the indi- "il' ll vidual layers being folded over onto one another with the incision disposed at the outer side of the fold, a row of bristles of U-shaped wires, and staples, one staple engaging the U-shaped bend of each bundle of wires and then passing through the felt at its incision into said base.

3. The combination with a base, of a double layer of felt composed of two individual layers defined from one another by an incision, the individual layers being folded over onto one another with the incision disposed at the outer side of the fold, a row of wire bristles disposed between said individual layers of felt, means for securing the inner ends of said bristles and said double layer of felt at its incision to said base, and means disposed to each side of said individual layers of felt to maintain them in place.

4. The combination with a base, of a double layer of felt composed of two individual layers defined from one another by an incision, the individual layers being folded over onto one another with the incision disposed at the outer side of the fold, a row of bristles of U-shaped wires, staples, one staple engaging the U-shaped bend of each bundle of wires and then passing through the felt at its incision into said base, and means disposed to each side of said individual layers of felt to maintain them in place.

5. The combination with a base, of outer longitudinally extending layers of felt, staples for securing the lower outer longitudinal edges of said outer layers to said base, two double layers of felt disposed inside of said outer layers, each double layer composed of two individual layers defined from one another by an incision, the individual layers being folded over onto one another with the incision disposed at the outer side of the fold, five rows of bristles of U-shaped wires, two rows of staples, each of said rows of staples having the staples thereof engaging the U- shaped bends of a row of bundles of wires and securing them to said base adjacent the inner face of each outer layer of felt, two other rows of staples, each of said other rows of staples having the staples thereof engaging the U-shaped bends of a row of bundles of wires and then passing through one of said double layers of felt at its incision into said base, and still another row of staples having the staples thereof engaging the U-shaped bends of still another row of bundles of wire and securing them to said base between said double layers of felt.

6. The combination with a base, of outer longitudinally extending layers of felt, staples for securing the lower outer longitudinal edges of said outer layers to said base, two double layers of felt disposed inside of said outer layers, each double layer composed of two individual layers defined from one another by an incision, the individual layers being folded over onto one another, with the incision disposed at the outer side of the fold, five rows of bristles of U-shaped wires, two rows of staples, each of said rows of staples having the staples thereof engaging the U-shaped bends of a row of bundles of Wires and securing them to said base adjacent the inner face of each outer layer of felt, two other rows of staples, each of said other rows of staples having the staples thereof engaging the U-shaped bends of a row of bundles of wires and then passing through one of said double layers of felt at its incision into said base, and still another row of staples having the staples thereof engaging the U-shaped bends of still another row of bundles of wires and securing them to said base between said double layers of felt, said layers of belt being crowded against said rows of bristles so that each bundle of bristles is actually surrounded by felt and thus separated from an adjacent bundle of bristles and securely anchored both in position and in erect condition.

7. The combination with a base, of outer longitudinally extending layers of felt, staples for securing the lower outer longitudinal edges of said outer layers to said base and thereby cause them to flex inwardly, and alternate longitudinal- 10o ly extending layers of felt and rows of wire bristles secured at their lower ends to said base, said alternate layers and rows being disposed between said outer layers of felt and thereby pressed inwardly toward one another, the outer edges of the layers of felt projecting beyond the outer edges of the wire bristles.

8. The combination with a base, of outer 1ongitudinally extending layers of felt, staples for securing the lower outer longitudinal edges of said outer layers to said base, a plurality of double layers of felt disposed between said outer layers, each double layer composed of two individual layers defined from one another by an incision, the 1 individual layers being folded over on to one another with the incision disposed at the outer side of the fold, a plurality of rows of bristles composed of bundles of U-shaped wires, and a plurality of rows of staples having the staples thereof engaging the U-shaped bends of the bundles of wires of said rows of bristles to secure them to said base adjacent the inner face of each outer layer of felt, between adjacent double layers of felt and between adjacent layers of each double layer.

ANTHONY A. ELNETT. 

